In vitro fecal fermentation demonstrates the prebiotic-like properties of quinoa modulated by different preparation methods

Quinoa grain represents an excellent source of nutrition, including protein, lipids, and fiber. Quinoa processing and cooking alters its chemical composition and bioavailability of nutrients, and while extracts have been studied, little is known about the impact of quinoa food products on the human gut microbiota. One selected quinoa line was tested in raw, boiled, extruded, and baked (cookie) forms for its ability to modulate fecal microbiota from 10 healthy donors. After <i>in vitro</i> digestion, samples underwent fecal fermentation with measurements taken at 0, 6, 12, 24, and 48 h (h). Boiled and extruded quinoa exhibited significantly higher total polyphenol content when compared to raw quinoa (p < 0.05), while baked quinoa had lower polyphenol content, though the difference was not significant. Fecal fermentation of pre-digested raw and processed quinoa significantly increased (p < 0.05) beneficial lactic acid-producing bacterial (LAB) genera, including <i>Bifidobacterium</i> and <i>Lactobacillus</i>. All quinoa samples (raw, boiled, extruded, and baked) significantly increased <i>Bifidobacterium</i> abundance from 6 to 48 h compared to the start of fermentation (0 h), while <i>Lactobacillus</i> increased significantly in boiled, baked, and extruded samples at 12-48 h. <i>Pediococcus</i> and <i>Weissella</i> were more abundant in raw quinoa, suggesting that less-processed plant material might be harder to ferment. These findings highlight quinoa's prebiotic properties, which are largely preserved across various cooking methods. Future studies on quinoa and other grain products should integrate food chemistry and gut microbiota outcomes to identify physicochemical properties that influence microbiota responses.